Air on an earth surface is influenced by solar energy, and an atmospheric temperature presents a periodical change along with a change of time. Water vapor in the air absorbs the solar energy and has a higher temperature, while liquid water on the earth surface absorbs solar thermal energy and is evaporated into gaseous water vapor, so that the air on the earth surface contains inexhaustible solar energy. At present, the solar energy can be used through many ways and methods including a solar photo-thermal method, a solar photoelectric method and the like. However, only radiation heat transfer in heat exchange is used in the utilization ways, and utilization efficiency is very low. Moreover, direct utilization of the solar energy in the air is relatively rare, and particularly approaches for absorbing the solar energy contained in the water vapor in the air are much fewer.
A novel functional mode of a heat source tower heat pump air conditioning system absorbing cold and heat sources in the air to serve as an air conditioning system by utilizing a heat source tower is applied. Due to excellent energy conservation and wide environmental suitability, the heat source tower heat pump air conditioning system has been widely applied to various architectural places in the middle and lower reaches of Yangtze River. In winter, the heat source tower serving as a good heat source collector extracts heat from low-temperature and humid ambient air to provide a heat source for a heat pump; and in summer, the heat source tower serving as a high-efficiency cooling tower discharges the heat absorbed by the heat pump from a user into an atmospheric environment. Thus, the heat source tower can be used both in winter and in summer, thereby saving initial investment and increasing an energy utilization rate.
At present, widely used heat source towers are classified into two major categories. One category is an open tower. An open heat source tower is proposed for providing the cold and heat sources for the air conditioning system in a utility model patent “heat source tower” with an application number of CN200620073647. The patent proposes that: a liquid inlet pipe is arranged on an upper part of the heat source tower; an end part of the liquid inlet pipe is connected with a sprayer; a heat exchange layer is arranged below the sprayer; a storage tank is arranged below a heat exchanger and provided with a liquid outlet pipe and a circulating pump; and an outlet of the circulating pump is connected with the liquid inlet pipe. The other category is a closed tower. A closed heat source tower is proposed to serve as a provider of the cold and heat sources of the air conditioning system in an invention patent “closed heat source tower” with an application number of CN200810031368. The invention patent proposes that: a low-temperature broadband heat exchanger composed of broadband fins and heat exchange tubes serves as a heat exchange apparatus of the heat source tower, and a negative-temperature frost prevention system composed of a solution pool, a spray pump energy storage control apparatus and the sprayer is utilized for frost prevention.
Since anti-freezing solution is always contacted with the air in an open tower system, heat exchange efficiency is higher, but a concentration of the anti-freezing solution is influenced by air humidity in the winter. In an actual operation, if the air has a low temperature and a high humidity, since the water vapor in the air is condensed into the liquid water to enter the anti-freezing solution when meeting cold air, the concentration of the anti-freezing solution is continuously decreased, and a freezing point rises, thereby increasing a hidden danger of freezing in a heat pump main engine; and if the air has a high temperature and a low humidity, moisture in the anti-freezing solution may be evaporated, and the concentration of the anti-freezing solution is increased, thereby decreasing the heat exchange efficiency of the heat pump. The concentration of the anti-freezing solution needs to be continuously adjusted in the open heat source tower system to prevent an extremely high or low concentration, so as to ensure that the system does not fail. Therefore, in order to guarantee a concentration range of the anti-freezing solution in the open heat source tower, various anti-freezing solution concentration control methods are adopted in patents, such as a utility model patent “heat source tower with solution regeneration function” with an application number of CN2011204759060, an invention patent “solution regeneration treatment apparatus” with an application number of 201210234947X, a utility model patent “waste heat utilization system for solution energy storage control apparatus” with an application number of 2012207346295, and the like. However, additional heat sources in different forms are needed in the various methods for heating the solution so as to achieve purposes of concentrating the anti-freezing solution and controlling the concentration of the anti-freezing solution, causing that economical efficiency is low and operation is complicated. Meanwhile, the anti-freezing solution in the open heat source tower is directly contacted with the air. Dust, bacteria, microbial waterweed and the like may be gathered in the anti-freezing solution to enter a heat exchange copper tube of the heat pump main engine and deposited on a tube wall, thereby greatly decreasing the heat exchange efficiency. On the other hand, although the anti-freezing solution in the closed tower is always isolated from the air, heat exchange efficiency of the closed tower is lower than that of the open system, so an area of the low-temperature broadband heat exchanger needs to be enlarged, thereby greatly increasing the initial investment.
Meanwhile, in the above air conditioning system, the heat source tower serves as the provider of the air conditioning cold and heat sources and has a low matching degree with an air conditioning main unit, so that problems of a poor heat exchange effect of the heat source tower and the air conditioning main unit, low overall efficiency of the system and the like are easily caused. In addition, in an air conditioning system used currently, condensate water of an indoor summer air conditioner of a user is generally dispersed or discharged outdoors or into a sewer line in a unified and centralized manner. Moreover, the condensate water of the air conditioner has a low temperature and is an excellent cold source of the air conditioning system. Since the condensate water cannot be utilized, waste of energy is caused.
In order to fully utilize high-efficiency heat exchange performance of the open heat source tower, avoid a defect of concentration change of the open heat source tower, ensure normal operation of the heat source tower heat pump system and increase working efficiency of the closed heat source tower heat pump system, design of a heat pump air conditioning system integrating high-efficiency heat exchange, cold energy recovery, controllable concentration, avoidance of gathering of impurities on the copper tube in the air conditioner main unit and increase of the heat exchange efficiency is inevitable.